University of Connecticut |
Polymer Program SeminarNew Functional and Long Chain Branched PP Polymers; Synthesis, Characterization, and Capacitor Applications Friday, March 24, 2006 11:00 am , IMS Room 20 One of the most unique developments in metallocene catalysis is the preparation of polyethylene with a long chain branching (LCB) molecular structure. Although only an extreme low concentration of long chain branches, the LCBPE material exhibits many unique rheological properties (shear thinning and high melt strength) that are very important for blown film applications. Despite intense research interest, so far there is no viable process for preparing long chain branched polypropylene (LCBPP). As a result, PP has been limited in some end-use fabrications, for example extrusion coating and blow molding. In addition, the processibility is also a major concern in the metallocene-prepared PP with narrow molecular weight distribution. In my presentation, I will discuss two new methods for preparing LCBPP polymers. The first one involves coupling reaction between chain end and side chain functionalized PP polymers with pre-determined structures; both are formed by new functionalization chemistry. The second method involves a simple (one-pot) metallocene-mediated propylene polymerization process in the presence of "T" reagent that can simultaneously serve as comonomer and chain transfer agent. The resulting LCBPP polymers were well-characterized by a combination of NMR spectra, GPC-triple detectors (Mark-Houwink plot), and rheology (melt viscosity and activation energy).In the last part of my presentation, I will focus on our current research activities of using LCBPP polymers for preparing ultrathin film and increasing dielectric properties of PP for high pulse and high energy capacitor applications.
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